Process for producing high energy fuels



Oct.` 27, 1959 E. W. GLUESENKAMP ETAL PROCESS FOR PRODUCING HIGH ENERGY FUELS Filed March 30. 1953 United States Patent Oice PROCESS FOR PRODUCING man ENERGY FUELS Earl W. Gluesenkamp and Milton Kosmin, Dayton, Ohio, assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware Application March 30, 1953,- Seal No'. 345,416

Claims. (Cl. 208-66) This invention relates to a process for producing improved high energy fuels and in particular to fuels suitable for use in turbo jet and turbo prop engines.

i `One object of this invention is to provide a process for producing a hydrocarbon fuel having substantially increased energy content per unit volume over hydrocarbon fuels of the prior art.

Another object of this invention is to provide a process for producing a hydrocarbon fuel for jet engines having a heat of combustion of from 125,000 to 160,000 B.t.u.s per gallon and more specifically from 136,000 to 150,000 B.t.u.s per gallon. Another object of this invention is to provide a process for producing a hydrocarbon fuel having a pour point (ASTM D 97-34 M) below -40 C.

An additional object of this invention is to provide a process for producing a hydrocarbon fuel for jet engines having a specific gravity from 0.85 at 30 C. to 1.5 at 30 C., and preferably from 0.90 at 30 C. to 1.00 at 30 C.

A still further object is to provide a process for producing a hydrocarbon fuel having a heat of combustion of from 125,000 B.t.u.s to 160,000 B.t.u.s per gallon and a pour point below 40 C. from naphthenic and parafnic hydrocarbons boiling in the gasoline and/or kero- `sene boiling range.

As pointed out in our copending application, Serial No. 316,312, tiled October 22, 1952, now U. S. Patent 2,765,617, issued October 9, 1956, of which the present application is a continuation-in-part, presentjet fuels have a heat of combustion of about 112,000 B.t.u.s per gallon and a relatively high pour or crystallization point. They are prepared from petroleum hydrocarbons in the naphtha and kerosene boiling range and accordingly consist largely of paraffnic and naphthenic hydrocarbons.

We have now found that high energy fuel having an extremely low pour point can be prepared from naphthenic hydrocarbons or from mixtures of naphthenic and paaffinic hydrocarbons by subjecting such mixtures to a catalytic reforming process, preferably in the presence of a noble metal catalyst of the platinum group, separating monocyclic aromatic hydrocarbons from the resulting mixture, and then subjecting the resulting aromatic hydrocarbon mixture to deep thermal conversion at a temperature of at least l100 lF., lwhereby polycyclic hydrocarbons are formed, then hydrogenating said polycyclic hydrocarbons to a substantially complete saturation.

The naphthenic hydrocarbons or mixtures of naphthenic and paranic hydrocarbons employed are essentially cyclic hydrocarbons including methyl cyclopentane, cyclohexane and methyl cyclohexane in admixture with straight or slightly branched open chain compounds. Aromatic compounds such as benzene, toluene and the xylenes may be present in the starting material.

The starting materials for the present process comprises petroleum distillates, such as naphthas or gasoline fractions having an initial boiling point ranging from about 70 F. to 150 F. and an end boiling point ranging from 250 F. to' about 425 F.- Such fractions Agenerally here-as an example of a suitable reforming catalyst, but

comprise mixtures of naphthenic and parainic hydrocarbons.

`In the reforming step the naphthenc hydrocarbons are dehydrogenated forming aromatic hydrocarbons and hydrogen, while the straight chain parains are hydrocracked and cyclicized and dehydrogenated likewise to aromatic hydrocarbons. The reforming step may be carried out with cataiysts of known compositions. Generally suitable catalysts comprise `alumina or silica or mixtures thereof formed by heat-treating suitable hydrous oxide gels, containing a minor percentage of platinum or palladium. Suitable catalysts contain from 0.01% to 1.5% platinum and are usually employed in the range of from 650 F. to 900 F. at pressures ranging from 150 to 800 pounds per square inch.

The hydrocracking reactions are those in which parain chains are severed, the reaction occurring in the presence of hydrogen. Cyclization occurs to some extent during this reaction. Generally, the catalyst is sufficiently selective so as to accomplish the desired cracking without the formation of excessive quantities of normally gaseous hydrocarbons such as methane, ethane and propane. It is necessary in order to obtain maximum selectivity to correlate the type of gasoline or naphtha fraction with the space velocity, temperature and pressure of the-reaction. When this is done, it is possible to obtain good conversions of the essentially parafinc hydrocarbons to cyclic cornpounds and eventually to aromatic hydrocarbons.

With certain catalysts and charge stocks it is possible to carry out the reforming operation simultaneously with the hydrocracking step. Generally, however, in order to obtain greater selectivity in these operations, it is desirable to carry out these processes separately, i.e., in sepa-` ordinarily be made up of a plurality of fractional distilla-A tion columns and associated lequipment as is well-understood in the art, a gasoline fraction is obtained via line 15 and a fraction higher boiling than gasoline composed of heavy naphtha and/ or kerosene is obtained via line 17. Light gases and liquefied petroleum gas can be removed las indicated by line 19, and the topped crude containing gas oil and heavier components is removed through line v ai.

1n one embodiment of our invention a full boiling range gasoline or a single selected cut thereof is introduced as by line 23 into a catalytic reforming operation of the nature described herein, represented by unit 25. A single cut rich in naplithenes can be subjected in unit `25 to simple naphthene dehydrogenation to form aromatic hydrocarbons. Part or all of the material characterized as heavy napntha and/ or kerosene can also be introduced to the catalytic reformer as by lines 27 and 29; Catalytic reforming unit 25 comprises one or more catalyst cases, into which there is also introduced a hydrogen-rich gas from line 31. Hydrocarbon charging stock and hydrogen are preheated by means not shown, to the desired reaction temperature.

A catalyst case (or cases) in reforming unit 25 con` tains a stationary bed of reforming catalyst, preferably one containing a small quantity of platinum or palladium supported on a synthetic silica-alumina gel having a comparatively low surface area, for example, 10 to 65 square meters per gram. 'Ihiscatalyst is mentioned Patented oci. 27, 1959A it will be understood from the discussion herein that a variety of reforming catalysts can be employed provided they at least effect dehydrogenation of naphthenes to aromatics, and preferably also effect dehydrocyclization of parafiins containing at least 6 carbon atoms per molecule to aromatics, dehydroisomerization of alkyl cyclopentanes to form aromatics and/r hydrocracking of heavy parans in the charge stock to lower molecular weight normally liquid parains, some of which in turn may undergo dehydrocyclization. It will be andestood that one catalyst will not be the full equivalent of another, and that the extent of conversion of charging stock to aromatic hydrocarbons will be dependent not only on the catalyst chosen but also on the character* istics of the feed stock and the conversion conditions employed. While a stationary bed of catalyst is the simplest embodiment, other methods of contacting reactants with solid catalysts, eg., in a fluidized bed or with ak moving catalyst bed, can be used if desired.

Total effluent from reforming unit 2S passes through line 33 into separator 35, first being cooled by means not shown. In separator 35 hydrogen-rich gas is separated as a gas phase and passed via lines 37 and 39 into a gas holder 4,1. Hydrogenarich gas from gas holder 41 is passed via lines 43 and 31 back to the reforming reaction being effected in unit 25. Alternatively, part or all of the hydrogen for the reforming can be recycled directly from line 37 via lines 45 and 31. Liquid is removed from separator or accumulator 35 through line 47 and passed to unit 49 wherein a separation is effected between aromatic hydrocarbons on the one hand and parafiinic hydrocarbons on the other hand. Usually essentially complete conversion of naphthenes to aromatics is effected in the catalytic reforming, but when substantial amounts of naphthenes are present in the liquid feed to separation uit 49, that unit is preferably operated so that residual naphthenes are recovered in admixture with the parans.

In unit 49 can be employed any procedure known to the art for effecting aromatic-paraffin separation. For example, the liquid hydrocarbons recovered from the catalytic reforming operation can be contacted in liouid' phase with a liouid solvent selective for aromatics. Alternatively, the liquid hydrocarbons can be subjected to extractive distillation whereby a paraffin-rich distillate is recovered and a liquid bottoms comprising aromatics dissolved in solvent is recovered, from which the aromatic hydrocarbons are then separated in known manner. Another alternative is to subject the liquid product of the catalytic reforming operation to contact with silica gel or other suitable adsorbent whereby aromatic hydrocarbons are adsorbed while paraffins pass through unadsorbed; the aromatic adsorbate is then desorbed by suitable means from the gel.

Numerous examples of each of these methods for separating aromatic hydrocarbons from parafiinic hvdrocarbons are well-known in the art and hence need not be discussed in great detail here. Thus, for example, brief discussions of a silica gel adsorption process, and extractive distillation process, and a liGuid-liquid solvent extraction process, are found in the Petroleum Refiner, vol. 30, No. 9, September 1951, at pages 227, 233, and 237, respectively.

In any event, a paraffin hydrocarbon product as free from aromatic hydrocarbons as economically feasible is recovered from separation unit 49 through line 51, and a highly aromatic hydrocarbon product is recovered through line 53. In the practice of our invention, it is not necessary that individual aromatic hydrocarbons produced in the catalytic reforming be separated one from the other as all can be recovered as a single stream of mixed aromatic hydrocarbons in line 53. However, in some instances it will be preferred to separate benzene, toluene, xylene, etc., from each other and subject each to optimum conditions in the deep pyrolysis step now to be discussed.

Aromatic hydrocarbons from line 53, mixed if desired with aromatic hydrocarbons from line 54 obtained by thermal or catalytic cracking of petroleum hydrocarbons including deep cracking of naphthas or of light hydrocarbon gases are obtained from coal tar, are heated by means not shown and subjected in unit 55 to a pyrolysis which is a non-catalytic deep thermal conversion at conditions including a temperature of at least 1100 and preferably at least 1400 F., resulting in the formation of polynuclear aromatic hydrocarbons, e.g., biphenyl, terphenyl and complex mixtures of polycyclic hydrocarbons, some of which may contain several benzene nuclei attached to and/or fused with each other and/ or joined with each other by one or more methylene groups.

The conditions for obtaining good yields of polynuclear hydrocarbons will depend somewhat upon the particular stock which is subjected to said deep thermal conversion. The temperatures will range upwardly from ll00 F. to say 1550 F., the higher temperatures within this range being employed when the stock is predominantly benzene, while the lower temperatures within the range are employed when substituted benzenes such as toluene, the xylenes or the ethylbenzenes are present in appreciable amounts in the charging stock. The time of sojourn of the hydrocarbon vapor within the pyrolysis tube is maintained within the range from about 4 seconds to about 30 seconds, the operating sojourn being related to the temperatures of the vapor undergoing conversion in such a manner that the shorter times of sojourn are employed with the higher temperatures and vice versa.

While the chemical reactions occurring during the deep thermal conversion step are not completely understood, it is thought that the aromatic hydrocarbons undergo dehydrogenation followed by fusion of the aromatic residues.

The gaseous product of the deep thermal conversion operation consists largely of hydrogen together with minor amounts of hydrocarbons such as methane, ethane, ethylene, etc. It is desired, however, to keep the formation of such normally gaseous hydrocarbon products at a minimum by suitable control of temperature and sojourn time in the deep thermal conversion tube. By so doing, the loss of valuable hydrocarbons is prevented and formation of carbon held to a minimum. It should be recognized that some charging stocks are more susceptible to the deposition of carbon or coke deposition in the pyrolysis tube than are others. In the event that coke-like deposits are formed within the pyrolysis tube, they can usually be removed simply by interrupting the stream of hydrocarbon vapors and passing an oxidizing gas such as air through the tubes until the carbon deposits have been burned of.

Apparatus suitable for the deep thermal conversion operation herein described is generally known to those skilled in the art. It comprises a preheater section in which the hydrocarbon vapors are brought up to the conversion temperature, and then introduced into the pyrolysis tubes. The preheater and pyrolysis tubes are heated by gas or oil burners, provision being made to maintain latter tubes at a substantially uniform temperature throughout their length. The preheater serves to heat the hydrocarbon vapor to the pyrolysis temperature without permitting any substantial amount of pyrolysis to occrr therein. Indeed all of the heat necessary to convert the hydrocarbons may be added in the preheating section and only so much heat supplied to the pyrolysis section as to prevent normal heat losses. When the vapors have reached the desired conversion temperature in the preheater, they enter the pyrolysis section and are then maintained at this temperature for a required time in order to permit the desired amount of deep thermal conversion to take place. The vapors leaving the pyrolysis tube are quickly cooled in order to stop any further reaction. Further cooling resulting in the production of a liquid c011- densate is then applied.

Total efuent from deep thermal conversion unit 55 is passed via line 57 and cooling means not shown into a separator 59 from which hydrogen is recovered overhead in line 61 and pyrolyzed liquid product is recovered in line 63. Hydrogen in line 61 is preferably passed via line 64 into gas holder 41 for admixture with hydrogen recovered from the reforming step and for use in the reforming step and in the dehydrogenation step to be described hereinbelow. If desired, part or all of the hydrogen in line 61 can be passed via lines 66 and 67 to the hydrogenation step.

Liquid is passed from line 63 into still 65 in which a separation is made between lower boiling unconverted aromatic hydrocarbons which are passed via lines 68 and 53 back to deep thermal conversion unit 55, and the polycyclic hydrocarbon mixture which is the product of the deep thermal conversion.

Polycyclic hydrocarbon mixture is recovered as bottoms through line 69 and passed to hydrogenation zone 71. Also into hydrogenation zone 71 is passed hydrogen from gas holder 41 via lines 72 and 67. This hydrogen can be derived in whole or in part from the hydrogen obtained by deep thermal conversion in unit 55 and hydrogen obtained by the dehydrogenation effected in reformer 25. Such hydrogen is passed into hydrogenation unit 71 through line 67 having been compressed by known means not shown to an effective hydrogenation pressure, e.g., 250 to 1000 pounds per square inch. In unit 71 the polycyclic hydrocarbon mixture is catalytically hydrogenated using any known hydrogenation catalyst, for example, metallic nickel obtained by decomposition of nickel formate, nickel-copper oxide-alumina, copper chromate. Hydrogenation is effected at such temperature, time and hydrogen pressure as to effect preferably substantially complete hydrogenation of the polycyclic hydrocarbons. Less preferably the hydrogenation can be carried only part way to form a partially hydrogenated polycyclic hydrocarbon mixture. This is a nondestructive hydrogenation and essentially theoretical yields of hydrogenated liquid polycyclic hydrocarbons are obtained.

The partially, or preferably completely, hydrogenated polycyclic hydrocarbon mixture thus foirned is separated from catalyst and hydrogen by known methods not shown and passed by line 73 into storage 75. This product from line 73 constitutes a high energy content jet fuel product of the present invention. It can be used per se as jet fuel, or blended with other fuel components, preferably hydrocarbons, to form a blended jet fuel.

By way of example, a few combinations of petroleum hydrocarbon charging stocks and reforming conditions will be discussed. It will be appreciated that numerous variations can be used in the catalytic reforming within the broad scope of the invention. For example, a Mid- Continent light naphtha cut having an initial boiling point of 130 F., 30 percent over boiling temperature of 240 F. and end point of 350 F., and containing about 50 percent parains, 35 percent naphthenes and 15 percent aromatics, can be contacted at 850 to 950 F., 500 p.s.i.g., a weight space velocity (weight of charge -per weight of catalyst per hour) of 2 to 4, and a hydrogenznaphtha mol ratio of 1, with a reforming catalyst composed of a steam treated synthetic silica-alumina having a surface area of 40 square meters per gram to which has been added about 0.5 weight percent platinum by impregnation of the steam-treated silica-alumina base with a solution of chloroplatinic acid followed by drying and reduction with hydrogen gas at an elevated temperature. The resulting reformate product is recovered almost without loss of volume and contains 50 weight percent aromatic hydrocarbons. As another example, a Mid-Continent straight run naphtha having a boiling range of 180 to 400 F. is reformed at 850 F., 500 p.s.i.,

a Weight space velocity of 2, and a'hydrogen:hydrocarbon mol ratio of 3:1, over a catalyst prepared by treating hydrous alumina with aqueous hydrogen fluoride, drying, pelleting, and then treating with chloroplatinic acid and ammonium hydroxide, followed by drying and calcining in air; the weight percent aromatic hydrocarbons in the product is 45 to 50 percent.

A less preferred but operable reforming catalyst is a synthetic chromia-alumina gel7 preferably in bead form. For example, such catalysts can be used to reform a wide variety of straight run naphthas, at a pressure of 200 pounds per square inch gauge, a temperature of 950-l000 F., and a 3:1 to 5:1 mole ratio of recycled hydrogen rich gas to naphtha feed stock, to produce a reformed gasoline containing from 35 to 50 volume percent aromatic hydrocarbons. Maximum percentage aromatics in the product is obtained with naphthas boiling within the range of 200 F. to 300 F.

Another very effective type of reforming catalyst includes those whose principal active constituent is molybdena, the commonest form being molybdena-alumina. Temperatures of 850 F. to l050 F. are suitable, and ordinarily hydrogen-rich gas is recycled.

The foregoing description of ow of materials relates to the treatment of a full range gasoline by catalytic reforming or single cut thereof `by catalytic reforming or' simple naphthene dehydrogenation. The remaining portion of the drawing now to be described illustrates additional and preferred embodiments of the invention.

While the paratins separated from the catalytic reforming effluent by separating means 49 can be employed in any desired manner, it is preferred that this material be passed via line 51 and line 77 to distillation unit 79 wherein a separation is effected between the lighter parans recovered in line 81 and heavier parains recovered in line 83. A cut-point between two fractions is chosen to give inthe light fraction only those paraflins most susceptible to dehydroaromatization, which occurs on passing the light cut from line 81 via line 29 back to reforming unit 25. The heavier parans can if desired also be returned by means not shown to reforming unit 25 for hydrocracking, but it is preferred that they be passed from line 83 into product storage tank 7S and blended therein with the hydrogenated polycyclic hydrocarbons to produce a blended jet fuel. In this manner that portion of the parafns recovered from the catalyticV reforming operation by means of separation unit 49, lines 51 and 77, still 79, and line 83, and which boil above,

say, 250 F., are utilized as components of a final jet fuel blend.

A further feature of the invention involves passage of the heavy naphtha and/or kerosene recovered from still 13 via line 17, to a solvent extraction unit 85 via line 87. By well-known solvent extraction procedures a separation is effected between the paraffnic components on the one hand and the aromatic and naphthenic components on the other hand; this often may require a multi-stage separation treatment. The heavy parains are recovered via line S9 and if desired can be passed via lines 91 and 83 into storage unit 75, becoming part of a final blended jet fuel product. Alternatively, part or all of the heavy paraflins can be passed from line 89 via line 29 to the catalytic reforming unit 25 for hydrocracking either in a single reforming operation or as a catalytic operation separate from naphthene dehydrogenation. Heavy aromatic and naphthenic hydrocarbons recovered by solvent extraction in unit 85 are passed via line 93 to still 65, wheel in admixture with the liquid eluent of the deep thermal conversion step, monocyclic hydrocarbons are recovered as a lighter fraction and passed via line 68 to deep thermal cracking unit 55 while polycyclic hydrocarbons are recovered by line 69 and passed to hydrogenation unit 71. By the described procedure of solvent extracting (in unit 85) the material in the crude oil boiling above thegasoline boiling range, and then separating the resulting aromatic-'naphthenic extract by distillation (in unit 65), the polycyclic hydrocarbon content of thisv heavier fraction of the crude oil is recovered and directly utilized Without the disadvantage of its being passed through catalytic reforming and/or hydrocracking procedures. Any heavy naphthene content of the extract passes unchanged through the hydrogenation lreaction elfected in unit 7l.

More selective reactions can be obtained in the catalytic reforming step of our process by first subjecting the gasoline from line l to a treatment termed super-fractionation represented diagrammatically by element 92 which can be fractional distillation procedures aided if desired by azeotropic distillation, extractive distillation, and/or solvent extraction procedures of known character. Normal pentane is removed by line 94 as it does not undergo useful reactions in catalytic reforming. Branched chain paraftins containing 5, 6 and 7 carbon atoms per molecule are recovered in a plurality of fractions indicated diagrammatically by lines 95 and 97 and employed as aviation gasoline blending stocks. Normal hexane and heptane are recovered as by lines 99 and lill and these stocks can be subjected to dehydroaromatization. This reaction can be effected in a general catalytic reforming or such conditions and catalysts optimum for dehydroaromatization can be applied to n-hexane and n-heptane, apart from the presence of other hydrocarbons. One or more fractions of low molecular Weight naphthenic hydrocarbons containing at least 6 carbon atoms per molecule are obtained as via lines l0?, and f0.5, and passed to a general catalytic reforming reaction or subjected to catalytic reforming conditions particularly adapted for and optimum for formation of aromatic hydrocarbons from these naphthenic hydrocarbons by dehydrogenation of cyclohexane rings and combined isomerization and dehydrogenation of alkyl cyclopentanes to form aromatic hydrocarbons. It is not feasible to attempt detailed segregation of components boiling above, say, 200 F. to 250 F., and therefore the heavier portion of the gasoline, boiling from temperatures in the neighborhood of 200 F. to 250 F. up to about 400 F., is recovered via line 107 and subjected to catalytic reforming in unit 25. It is thus apparent that one or more fractions of desired chemical and physical characteristics can be separated out from the gasoline material in order to obtain the most benecial effects from the catalytic reforming, which reforming can be of the type wherein several different reactions occur concomitantly, or can be restricted to a straight-forward single reaction for the purpose of forming aromatic hydrocarbons and/or hydrocracking as the case may be a plurality of such single reactions often being effected simultaneously but in separate reactors.

While the invention has been described herein with particular reference to various preferred embodiments thereof, it will be appreciated that variations from the details given herein can be effected without departing from the invention in its broadest aspects.

We claim: Y

l. A process for producing a high boiling hydrogenated polycyclic hydrocarbon high energy fuel Which comprises subjecting a hydrocarbon stock of relatively high naphthene content to catalytic reforming, whereby contained naphthenes are substantially dehydrogenated and isomerized to aromatics, separating monocyclic aromatic hydrocarbons from the resulting product, subjecting said monocyclic aromatic hydrocarbons to non-catalytic deep thermal conversion at conditions including a temperature of at least ll00 F. resulting in the formation of higher boiling polycyclic aromatic hydrocarbons, and hydrogenating said polycyclic aromatic hydrocarbons to substantially complete saturation thereby forming a high energy fuel product higher boiling than the initial feed to the process.

2. A process for producing a high boiling hydrogenated version at conditions including a temperature of at least 1l00 F. resulting in the formation of higher boiling polycyclic aromatic hydrocarbons, and hydrogenatingsaid polycyclic aromatic hydrocarbons to from partial to substantially complete saturation thereby forming a high energy fuel product higher boiling than the initial feed to the process.

3. A process for producing a high boilinghydrogenated polycyclic hydrocarbon high energy fuel which comprises subjecting a petroleum naphtha of relatively high naphthene content to catalytic reforming in the presence of hydrogen and in the presence of a platinum-containing catalyst whereby contained naphthenes are substantially dehydrogenated and isomerized to aromatics and contained paraffins are dehydroaromatized, under conditions effecting a net production of hydrogen, separating monocyclic aromatic hydrocarbons from the resulting product, subjecting said monocyclic aromatic hydrocarbons to noncatalytic deep thermal conversion at conditions including a temperature of at least 1100o F. resulting in the formation of higher boiling polycyclic aromatic hydrocarbons, and hydrogenating said polycyclic aromatic hydrocarbons to substantially complete saturation With hydrogen derived from said deep thermal conversion and from said catalytic reforming thereby forming a high energy fuel product higher boiling than the initial feed to the process.

4. The process for producing a high boilingvhydrogenated polycyclic hydrocarbon high energy fuel which comprises subjecting a petroleum naphtha containing naphthene hydrocarbons and paraffin hydrocarbons to catalytic reforming under conditions effecting dehydrogenation of cyclohexane naphthenes to aromatics, dehydroisomerization of alkyl cyclopentane naphthenes to aromatics, hydrocracking of high-boiling parathns to lower-boiling normally liquid parans, and dehydroaroma tizing paraflins to aromatics, separating monocyclic aromatic hydrocarbons from the resulting product, subjecting said monocyclic aromatic hydrocarbons to non-catalytic deep thermal conversion at conditions resulting in the formation of higher boiling polycyclic aromatic hydrocarbons therefrom, and catalytically hydrogenating said polycyclic aromatic hydrocarbons to produce a high energy fuel having a heat of combustion of from 125,000 to 160,000 B.t.u.s per gallon and higher boiling than the initial feed to the process.

5. A process for producing a high boiling hydrogenated polycyclic hydrocarbon high energy fuel which comprises subjecting a hydrocarbon stock of relatively high naphthene content to catalytic reforming in the presence of hydrogen, whereby contained naphthenes are substantially dehydrogenated and isomerized to aromatics and a net productionof hydrogen is effected, separating monocyclic aromatic hydrocarbons from the resulting product, subjecting said monocyclic aromatic hydrocarbons to noncatalytic deep thermal conversion at conditions resulting in the formation of higher boiling polycyclic aromatic hydrocarbons and hydrogen, said hydrogen for catalytic reforming being obtained from both said net production of hydrogen therein and said deep thermal conversion, and hydrogenating said polycyclic aromatic hydrocarbons to from partial to complete saturation to form said high energy fuel product higher boiling than the initial feed to the process.

6. A process for producing a high boiling hydrogenated polycyclic hydrocarbon high energy fuel which comprises subjecting a hydrocarbon stock of relatively high naphthene content to catalytic reforming in the presence of hydrogen, whereby contained naphthenes are substantially dehydrogenated and isomerized to aromatics and a net production of hydrogen is effected, separating monocyclic aromatic hydrocarbons from the resulting product, subjecting said monocyclic aromatic hydrocarbons to noncatalytic deep thermal conversion at conditions resulting in the formation of higher boiling polycyclic aromatic hydrocarbons and hydrogen, said hydrogen for catalytic reforming being obtained both from said net production of hydrogen therein and said deep thermal conversion, and hydrogenating said polycyclic aromatic hydrocarbons with hydrogen derived from said net hydrogen production in said catalytic reforming and from said deep thermal conversion to from partial to complete saturation to form said high energy fuel product higher boiling than the initial feed to the process.

7. A process for producing a high boiling hydrogenated polycyclic hydrocarbon high energy fuel which comprises subjecting a hydrocarbon stock of relatively high naphthene content to catalytic reforming whereby contained naphthenes are substantially dehydrogenated and isomerized to aromatics, separating resulting product into a monocyclic aromatic hydrocarbon rich portion and a paraflinic hydrocarbon rich portion, subjecting the former to non-catalytic deep thermal conversion at conditions including a temperature of at least 1100 F. resulting in the formation of higher boiling polycyclic aromatic hydrocarbons, hydrogenating said polycyclic aromatic hydrocarbons to from partial to substantially complete saturation thereby forming a high energy fuel product higher boiling than the initial feed to the process, and blending same with at least part of said paraflinic hydrocarbon rich portion to produce a blended high energy jet fuel.

8. A process for producing a high boiling hydrogenated polycyclic hydrocarbon high energy fuel which comprises subjecting a hydrocarbon stock of relatively high naphthene content to catalytic reforming whereby contained naphthenes are substantially dehydrogenated and isomerized to aromatics, separating resulting product into a monocyclic aromatic hydrocarbon rich portion and a paratiinic hydrocarbon rich portion, subjecting the former to non-catalytic deep thermal conversion at conditions including a temperature of at least 1100u F. resulting in the formation of higher boiling polycyclic aromatic hydrocarbons, hydrogenating said polycyclic aromatic hydrocarbons to from partial to substantially complete saturation thereby forming a high energy fuel product higher boiling than the initial feed to the process,

separating said paraflinic hydrocarbon rich portion into a lower boiling cut and a higher boiling cut, returning said lower boiling cut to said catalytic reforming, and blending said higher boiling cut with said high energy fuel product resulting from said hydrogenation to form a blended high energy jet fuel.

9; A process for producing a high boiling hydrogenated polycyclic hydrocarbon high energy fuel which comprises subjecting a gasoline boiling .range hydrocarbon stock of relatively high naphthene content to catalytic reforming whereby contained naphthenes are substantially dehydrogenated and isomerized to aromatics, separating monocyclic aromatic hydrocarbons from the resulting product, subjecting said monocyclic aromatic hydrocarbons to non-catalytic deep thermal conversion at conditions including a temperature of at least 1100" F. resulting in the formation of higher boiling polycyclic aromatic hydrocarbons, subjecting effluent from said deep thermal conversion to distillation to separate monocyclic hydrocarbons from polycyclic hydrocarbons, subjecting a hydrocarbon stock higher boiling than said gasoline range stock and derived from the same source material to solvent extraction and thereby obtaining an extract comprising heavy aromatic and naphthenic hydrocarbons, introducing said extract into said distillation, passing monocyclic hydrocarbons obtained from said distillation to said deep thermal conversion step, and subjecting polycyclic hydrocarbons obtained from said distillation to hydrogenation to form a high energy fuel product higher boiling than the initial feed to the process.

10. A process according to claim 9, wherein a raffinate comprising heavy paraiiinic hydrocarbons obtained by said solvent extraction is passed to said catalytic reformlng.

References Cited in the file of this patent UNITED STATES PATENTS 2,328,828 Marschner Sept. 7, 1943 2,339,246 Bates et al. Jan. 18, 1944 2,342,888 Nysewander et al. Feb. 29, 1944 2,345,575 Burk et al. Apr. 4, 1944 2,431,515 Shepardson Nov. 25, 1947 2,479,110 Haensel Aug. 16, 1949 2,522,696 Watson Sept. 19, 1950 2,559,285 Douce July 3, 1951 2,573,726 Porter et al Nov. 6, 1951 

1. A PROCESS FOR PRODUCING A HIGH BOILING HYDROGENATED POLYCYCLIC HYDROCARBON HIGH ENERGY FUEL WHICH COMPRISES SUBJECTING A HYDROCARBON STOCK OF RELATIVELY HIGH NAPHTHENE CONTENT TO CATALYTIC REFORMING, WHEREBY CONTAINED NAPHTHENES ARE SUBSTANTIALLY DEHYDROGENATED AND ISOMERIZED TO AROMATICS, SEPARATING MONOCYCLIC AROMATIC HYDROCARBONS FROM THE RESULTING PRODUCT, SUBJECTING SAID MONOCYCLIC AROMATIC HYDROCARBON TO NON-CATHALYTIC DEEP THERMAL CONVERSION AT CONDITIONS INCLUDING A TEMPERATURE OF AT LEAST 1100*F. RESULTING IN THE FORMATION OF HIGHER BOILING POLYCYCLIC AROMATIC HYDROCARBONS AND HYDROGEN ATING SAID POLYCYCLIC AROMATIC HYDROCARBONS TO SUBSTANTIALLY COMPLETE SATURATION THEREBY FORMING A HIGH ENERGY FUEL PRODUCT HIGHER BOILING THAN THE INITIAL FEED TO THE PROCESS. 